lang: Fix parsing for bytes literals in the IDL

[Aursen]

This is just a small correction for the generation of idl constants.

For example:

#[constant]
pub const BYTES_STR: &[u8] = b"test";

#[constant]
pub const BYTE_STR: u8 = b't';

It was generated like that before:

{
  "name": "BYTES_STR",
  "type": {
    "defined": "&[u8]"
  },
  "value": "b\"test\""
},
{
  "name": "BYTE_STR",
  "type": "u8",
  "value": "b't'"
}

Now:

{
  "name": "BYTES_STR",
  "type": "bytes",
  "value": "[116, 101, 115, 116]"
},
{
  "name": "BYTE_STR",
  "type": "u8",
  "value": "116"
}

Feel free to make comments especially on the quality of the code

[vercel]

@Aursen is attempting to deploy a commit to the coral-xyz Team on Vercel.

A member of the Team first needs to authorize it.

[Henry-E]

• it adds functionality that fixes some kind of small issue
• it adds a test to confirm this new functionality works
  Looks like a merge to me